Marine oils with iodine values in the range 83–108 from Newfoundland turbot or Greenland halibut (Reinhardtius hippoglossoides), sablefish (Anoplopoma fimbria), and certain Atlantic herring (Clupea harengus), were examined for fatty acid composition by gas–liquid chromatography. The herring oils differed from the other oils in having high levels of C20and especially C22fatty acids (chiefly monounsaturated). The sablefish oil had a high level of C18fatty acids, the turbot oil a composition intermediate between the herring and sablefish oils. All of these oils contained moderate amounts of polyunsaturated fatty acids (7.3–14.4%). The low iodine values were primarily due to monounsaturated fatty acids and not to saturated fatty acids (17.1–21.0%)